6888-79-5Relevant academic research and scientific papers
1,3-Difunctionalization of β-alkyl nitroalkenes via combination of Lewis base catalysis and radical oxidation
Wang, Ye,Zheng, Lei,Shi, Xiaodong,Chen, Yunfeng
supporting information, p. 886 - 889 (2021/02/01)
Upon treatment with a Lewis base catalyst, β-alkyl-substituted nitroalkenes could be readily converted into allylic nitro compounds. Examples of either C-1 or C-3 functionalization methods have been reported through nitro-elimination, giving alkene products. In this work, successful 1,3-difunctionalization was achieved through a synergetic Lewis base catalysis and TBHP radical oxidation, giving vinylic alkoxyamines in good to excellent yields. This work further extended the general synthetic application of β-alkyl nitroalkenes.
Formal Allylation and Enantioselective Cyclopropanation of Donor/Acceptor Rhodium(II) Azavinyl Carbenes
Liu, Zhili,Chen, Lianfen,Zhu, Dong,Zhu, Shifa
supporting information, p. 1275 - 1279 (2021/02/20)
A highly efficient formal allylation of dihydronaphthotriazoles with alkenes under rhodium(II) catalysis is reported. Various allyl dihydronaphthalene derivatives were furnished via rhodium(II) azavinyl carbenes with moderate to good yields and excellent chemoselectivity. When monosubstituted alkenes are used, cyclopropanation occurs and good to excellent enantioselectivities have been achieved. Particularly noteworthy is the allylic C(sp2)-H activation instead of traditional C(sp3)-H activation in the formal allylation process.
Palladium-Catalyzed Markovnikov Hydroaminocarbonylation of 1,1-Disubstituted and 1,1,2-Trisubstituted Alkenes for Formation of Amides with Quaternary Carbon
Yang, Hui-Yi,Yao, Ya-Hong,Chen, Ming,Ren, Zhi-Hui,Guan, Zheng-Hui
supporting information, p. 7298 - 7305 (2021/05/26)
Hydroaminocarbonylation of alkenes is one of the most promising yet challenging methods for the synthesis of amides. Herein, we reported the development of a novel and effective Pd-catalyzed Markovnikov hydroaminocarbonylation of 1,1-disubstituted or 1,1,2-trisubstituted alkenes with aniline hydrochloride salts to afford amides bearing an α quaternary carbon. The reaction makes use of readily available starting materials, tolerates a wide range of functional groups, and provides a facile and straightforward approach to a diverse array of amides bearing an α quaternary carbon. Mechanistic investigations suggested that the reaction proceeded through a palladium hydride pathway. The hydropalladation and CO insertion are reversible, and the aminolysis is probably the rate-limiting step.
Ni-Catalyzed Reductive Allylation of α-Chloroboronates to Access Homoallylic Boronates
Lou, Yixian,Qiu, Jian,Yang, Kai,Zhang, Feng,Wang, Chenglan,Song, Qiuling
supporting information, p. 4564 - 4569 (2021/06/28)
The transition-metal-catalyzed allylation reaction is an efficient strategy for the construction of new carbon-carbon bonds alongside allyl or homoallylic functionalization. Herein we describe a Ni-catalyzed reductive allylation of α-chloroboronates to efficiently render the corresponding homoallylic boronates, which could be readily converted into valuable homoallylic alcohols or amines or 1,4-diboronates. This reaction features a broad substrate scope with good functional group compatibility that is complementary to the existing methods for the preparation of homoallylic boronates.
Visible-light-promoted radical alkylation/cyclization of allylic amide with N-hydroxyphthalimide ester: Synthesis of oxazolines
Ding, Hao,Huang, Panyi,Jin, Can,Su, Weike,Sun, Bin,Yan, Zhiyang,Zhao, Haiyun
supporting information, (2021/10/29)
An efficient photocatalytic alkylation/cyclization of allylic amide with N-hydroxyphthalimide ester has been developed. The transformation is taken advantage of alkyl radicals to attack allylic amide with the assist of inexpensive rose bengal as photocatalyst to prepare a series of alkyl substituted oxazolines in moderate to excellent yields. High regioselectivity, operational safety, mild conditions and excellent substrate generality give this protocol broad application prospects.
MnBr2 catalyzed regiospecific oxidative Mizoroki-Heck type reaction
Chen, Xiang,Chen, Yi-Hung,Liu, Shanshan,Shen, Xiao,Zhu, Zhihong
supporting information, (2021/11/27)
Herein, we report an unprecedented regiospecific oxidative Mizoroki-Heck type reaction for the synthesis of ɑ-difluoromethyl homoallylic alcohols. The reaction shows broad substrate scopes and high functional group tolerance. Late-stage functionalization of complex biologically active molecules demonstrates the synthetic potential of this transformation. Mechanistic study supports the involvement of MnBr2 catalyzed radical 1,2-silyl transfer.
A donor-acceptor complex enables the synthesis of: E -olefins from alcohols, amines and carboxylic acids
Chen, Kun-Quan,Shen, Jie,Wang, Zhi-Xiang,Chen, Xiang-Yu
, p. 6684 - 6690 (2021/05/31)
Olefins are prevalent substrates and functionalities. The synthesis of olefins from readily available starting materials such as alcohols, amines and carboxylic acids is of great significance to address the sustainability concerns in organic synthesis. Metallaphotoredox-catalyzed defunctionalizations were reported to achieve such transformations under mild conditions. However, all these valuable strategies require a transition metal catalyst, a ligand or an expensive photocatalyst, with the challenges of controlling the region- and stereoselectivities remaining. Herein, we present a fundamentally distinct strategy enabled by electron donor-acceptor (EDA) complexes, for the selective synthesis of olefins from these simple and easily available starting materials. The conversions took place via photoactivation of the EDA complexes of the activated substrates with alkali salts, followed by hydrogen atom elimination from in situ generated alkyl radicals. This method is operationally simple and straightforward and free of photocatalysts and transition-metals, and shows high regio- and stereoselectivities.
Deoxyfluorination with CuF2: Enabled by Using a Lewis Base Activating Group
Bode, Bela E.,Chabbra, Sonia,Champion, Sue,Dawson, Daniel M.,Sood, D. Eilidh,Sutherland, Andrew,Watson, Allan J. B.
supporting information, p. 8460 - 8463 (2020/04/10)
Deoxyfluorination is a primary method for the formation of C?F bonds. Bespoke reagents are commonly used because of issues associated with the low reactivity of metal fluorides. Reported here is the development of a simple strategy for deoxyfluorination, using first-row transition-metal fluorides, and it overcomes these limitations. Using CuF2 as an exemplar, activation of an O-alkylisourea adduct, formed in situ, allows effective nucleophilic fluoride transfer to a range of primary and secondary alcohols. Spectroscopic investigations have been used to probe the origin of the enhanced reactivity of CuF2. The utility of the process in enabling 18F-radiolabeling is also presented.
Difluorocarbene Generation from TMSCF3: Kinetics and Mechanism of NaI-Mediated and Si-Induced Anionic Chain Reactions
García-Domínguez, Andrés,West, Thomas H.,Primozic, Johann J.,Grant, Katie M.,Johnston, Craig P.,Cumming, Grant G.,Leach, Andrew G.,Lloyd-Jones, Guy C.
supporting information, p. 14649 - 14663 (2020/10/13)
The mechanism of CF2 transfer from TMSCF3 (1), mediated by TBAT (2-12 mol %) or by NaI (5-20 mol %), has been investigated by in situ/stopped-flow 19F NMR spectroscopic analysis of the kinetics of alkene difluorocyclopropanation and competing TFE/c-C3F6/homologous perfluoroanion generation, 13C/2H KIEs, LFERs, CF2 transfer efficiency and selectivity, the effect of inhibitors, and density functional theory (DFT) calculations. The reactions evolve with profoundly different kinetics, undergoing autoinhibition (TBAT) or quasi-stochastic autoacceleration (NaI) and cogenerating perfluoroalkene side products. An overarching mechanism involving direct and indirect fluoride transfer from a CF3 anionoid to TMSCF3 (1) has been elucidated. It allows rationalization of why the NaI-mediated process is more effective for less-reactive alkenes and alkynes, why a large excess of TMSCF3 (1) is required in all cases, and why slow-addition protocols can be of benefit. Issues relating to exothermicity, toxicity, and scale-up are also noted.
Cu/Ni-Catalyzed Cyanomethylation of Alkenes with Acetonitrile for the Synthesis of β,γ-Unsaturated Nitriles
Jian, Hong,Shen, Zengming,Zhang, Saisai
, p. 6143 - 6150 (2020/05/22)
We have developed a protocol for the Cu/Ni-catalyzed cyanomethylation of alkenes with acetonitrile for the synthesis of β,γ-unsaturated nitriles. This is the first example of a direct coupling of the alkene sp2 C - H bond and the acetonitrile sp3 C - H bond for the preparation of β,γ-unsaturated nitriles. Acetonitrile, an inexpensive and stable solvent, is demonstrated to be a useful cyanomethyl source. The combination of copper and nickel catalysts resulted in a high reaction efficiency.
